Aliasing star_trek:_the_next_generation → star_trek_the_next_generation
Link to alias

Reason:

Since the rest of the Star Trek series tags are without colon (:) :
1) 96 . . . star_trek_the_animated_series
2) 21 . . . star_trek_the_original_series
3) 4 . . . star_trek_deep_space_9
4) 4 . . . star_trek_voyager

and the logo in the title sequence (near start of episodes) just says "Star Trek The Next Generation" (except in ALL CAPS).

EDIT: The tag alias star_trek:_the_next_generation -> star_trek_the_next_generation (forum #260254) has been approved by @bitWolfy.